He IS replacing Sam Cassell
Yes, Stephon Marbury is struggling. But let's not go crazy here. The guy is replacing Sam Cassell. After a couple of nice games in Celtic greem, Cassell went through a five game rut just as bad as Marburry's when he show 4 - 24 with 11 assists and 8 turnovers. Marbury hasn't been great, or even good, or even mediocre, but let's not pretend that the Sam Cassell Era featured a ton of highlights. And, thankfully, I haven't yelled "Stop shooting!" once so far whereas Cassell was launching shots at an almost comical pace the moment he stepped on the floor.
Mikki Moore is, no pun intended, more of an issue because I just don't see him replacing PJ Brown's effectiveness and veteran savvy. I'm sure Danny Ainge has been on the phone with PJ seeing if there is any way that they can lure him out to retirement. Since Brown is a restricted free agent, he can sign with the Celtics at any time before the playoff rosters need to be set and still be able to play in the second season. I'm pretty sure that's the rule (at least that was the rule in 2006).
If Brown won't come back, and players we sign can still be eligible for the playoff roster, who else might we look at?
At the point guard spot, I'd take a look at Marcus Williams. Yes, he's a bit of a headcase but I think he's someone that could work well in the right situation. The power forward list is more interesting because it includes the green lightning rod himself, Antoine Walker. There's also Paul Davis, Robert Horry, and the combo-forward Ruben Patterson. Of course, most of those guys have the Marbury issue of not having played for a while.
Still, Antoine back in Beantown would be interesting to say the least.